1. Field of the Invention
The present invention relates to a control device and a control method for a vehicle; and, more particularly, to a technology for controlling a vehicle to output torque, determined in accordance with a rotational speed (rpm) of the output shaft of a power source.
2. Background of the Invention
Conventionally, a vehicle having an electronic throttle valve driven by a motor are known. The opening degree of the electronic throttle valve, i.e. the throttle opening degree, is controlled in accordance with the operation amount of an accelerator. In such a vehicle having the electronic throttle valve, there has been proposed an engine control technology wherein a target torque of an engine is set based on the accelerator operation amount and the throttle opening degree is then set in accordance with the target torque to thereby control the engine.
Japanese Patent Application Publication No. 2002-195087 (JP-A-2002-195087) describes an engine control device for a vehicle, which controls the output of an engine by setting a target engine torque and then controlling a throttle valve on the basis of the target engine torque. The engine control device includes a calculation part for calculating a correction quantity for a target engine torque through a surface-interpolation in which, by using a map having a transmission ratio and an engine speed (rpm) as lattice axes, the interpolation is performed in the directions of the transmission ratio and the engine speed; and a correction part correcting the target engine torque based on the correction quantity.
In accordance with the engine control unit described in JP-A-2002-195087, the throttle opening degree is controlled by calculating a correction quantity for the target engine torque by using the surface-interpolation map having the transmission ratio and the engine speed as the lattice axes and correcting the target engine torque based on the correction quantity. Accordingly, a desired engine torque depending on an increase of the engine rotational speed can be obtained at any transmission position.
However, in the engine control unit described in JP-A-2002-195087, wherein the target engine torque is to be corrected, the corrected target engine torque may be insufficient if the target engine torque is small. In this case, it is difficult to know whether the corrected target engine torque, i.e. the actual torque output, is really being varied depending on the engine speed.